In this talk, we will present the successful synthesis of two new Kitaev spin liquid candidate materials, RuBr3[1] and RuI3[2], via the high-pressure method. We believe that these are New Kitaev spin liquid candidate materials like α-RuCl3 which is the most probable candidate material for the Kitaev quantum spin liquid. RuBr3 possesses an ideal honeycomb lattice of Ru3+ with R-3 symmetry and shows the antiferromagnetic order with zigzag-type magnetic structure at TN = 34 K. The moment angle from honeycomb plane in RuBr3 is larger than that in α-RuCl3, suggesting larger Kitaev interactions in RuBr3 compared to α-RuCl3. On the other hand, there are two kinds of polymorph in RuI3 with the honeycomb lattice; R-3 and P-31c. RuI3 with the honeycomb structure shows a semi-metallic feature in the electrical resistivity and no magnetic order down to the lowest measurement temperature. Metal-insulator transition occurs by an introduction of iodine for halogen site X in RuX3. In our presentation, we will show an electronic phase diagram of RuX3 and discuss the effect of bandwidth control in Ruthenium trihalides.
[1] Y. Imai et al., Phys. Rev. B 105, L041112 (2022).
[2] K. Nawa, Y. Imai et al., J. Phys. Soc. Jpn. 90, 123703 (2021).